Receiving apparatus



Aug. 16, 1932. 1,872,634

H. J. J. M. DE REGNAULD DE BELLESCIZE RECEIVING APPARATUS Filed July 7 1928 @HIE INVENTOR H.J.J. M. DE nseuauu) n2 BELLESUZE Bi/b ORNEY Patented Aug. 16, 1932 UNHTE D STATES PIA-TENT ormE.

HENRI JEAN JOSEPH lVIARIE nE EEG AULD DE EELLEsoIZE, 0E PARISIEEANCE, AS-

SIGNOB T0 COMPAGNIE GENEEALE DE TELEGRAPHIE SANS EIL, OF'PARIS, FRANCE,

A JOINT-STOCK COMPANY OF FRANCE RECEIVING APPARATUS Application filed July r, 1928', Serial mama, and in F rance July 13; 1927.

consists in causingthese two oscillations to act upon different electrodes, and this results in modulating one of these oscillations by the other oscillation.

In accordance with the present invention as illustrated in Figs. 1 and 2, it is possible to combine these two methods and thus increase to a considerable degree the amplitude of the oscillation of mean frequency produced in the receiver, the mean frequency being the inaudible intermediate frequency obtained by lowering the incoming signal frequency.

The invention is more clearly understood by reference to the drawing, wherein Fig. 1 represents the circuit arrangement for one form of the invention, Fig. 2 represents the .circuit arrangement for a modification where- .in a selfregenerative tube is used and Fig.

2a is a circuit analysis of the arrangement of As shown in Fig. 1 the signal is picked up by a resonator 1 consisting, for instance, of a coil antenna or frame tuned to the pulsation and itactuates one of the grids, say 7, confined within a two-gridtube, while the other grid 6 is subjected to the oscillations created by the local generator or heterodyne Qtuned to wave-length o This'arrangement results in a current having a mean frequency of w a or co -(o depending on whether'o 'is smaller or larger than m 'Upon'this modulation method the beat method is superposed as follows: The grid 7 upon which the signal is broughtto .act is connectedwith therotor united with'two points 9 andlO of thelocal generator or heterodyne and are of opposite polarity. If H sin (o t-Pt) denotes the pobe applied to the resonator 1, and as a result according to whether the heterodyne istuned tentialof the plate 12, that of the plate 13 Wlll consequently be H sin (w t'tilld'vr) The couplings 1112 and 1113'cause an electromotlve force due to the local generator to current having frequency M which is superposed upon the signal current and is brought to interfere with it, the .two acting combinedly uponthe same electrode '7. Hence, the two frequency changing methods are employed at the same time. 7

But their actions may either neutralize or reinforce each other. vApartfrom the fact that the electromotive force set up by the local ge'nerator2 in the resonator lniay be reversed according to whether one ofthe couplings 1112 or 1113 is used,'the auxiliary oscillation due tothis electromotive force'may be displaced in phase either by to'a. wave-length below the wave-length of the signal (ui w or above the same u o) Hence, four combinations are realizable, to wit:

30 (0 0 wlth coupl1'11g'11'12 a m with coupling 11-12 w w with coupling 1113 axe. with coupling'll l3 The a'foregoing'conclusions may be dediiced' f'romthe following theoretical considerations. "\/V ith're gard to the high frequency, thefterminals of the condenser, shunting the plate battery (Fig. 2), have practically the same potential; taking it as the original one, it can be stated that: r K

S sin w t the signal potential at the grid 7 7L sin (w t+') =the'p0tential produced by the heterodyneat the plate 8. i

The direction of the circulation of the heterodyne. current in the coils 1 and 1 being' given, the potential; produced by I the heterodyne at the'second-grid tl has approximately the value (the condenser 10, installed for the mean frequency, acting almost like a short-circuit for the high frequency) It will be recalled in the first place that the invention has as its sole object to superpose two modulation systems and to amplify one by the other.

The first modulation system is the one which may be observed in a tube in which two electrodes are simultaneously submitted to two oscillations; there is obtained a known plate current in which figures, amongst other things, the product of the two oscillations.

Here, one of them is the signal, the other the heterodyne. The result is:

The term represents the first current of modulation which is utilized in the receiver.

The second modulation is obtained by superposing, in the usual manner, the oscillations of the signal and the heterodyne on a same electrode and by detecting the resulting oscillation.

The grid 7 is already the seat, with respect to the signal, of the oscillation 5 sin w t On it is superposed the one of the bet erodyne by means of the electrostatic couplingof one of the condensers 11, 12 or 11, 13 but the sign of the coupling is not arbitrary, the second modulation thus obtained reinforcing the first in one operating sense and chokingthe same in the other sense.

In fact, if C designates the coupling capacity (11, 12 of 1113) between the heterodyne and the circuit 1, and o the potential of the heterodyne excitation, (which is eX- pressed by according to whether the grid 7 is electrostatically coupled with the plate 8 or the other grid 6), then the potential produced by the heterodyne at the top of the resonator 1 (LC), in other words at the grid (7), may be found according to the analysis in Fig. 2a in which I put:

LCM/' L (0+ Ugh/ +16 In the calculation leading to this result there is implicity made an approximation, namely that the electrostatic coupling C produced between the resonator 1 and the heterodyne resonator, will not appreciably modify the voltage 1; of thislatter. This is a legitimate assumption since the coupling is extremely loose and the two resonators are distinctly out of tune. C is always very small with respect to C; while the heterodyne has as pulsation (0 the resonator 1 has the pulsation m of the signal:

will be greater than 1; u is a phase with o, On the other hand, for w w u is in opposition to 'v. In the application the oscillations of the current have been assumed as produced in the resonator 1 by the heterodyne; the current being, as known, at 90 with respect to the potential, u will be displaced by 1 (d) C corresponds to a coupling 11, 12;

m w then 41=H sin (w t+1//+1r) U=U sin w t++1r+11') =U sin (w H- b) The sum of the oscillations (signal plus heterodyne) superposed in this manner on the grid 7 has, therefore, the value:

8' sin (0 6+ U sin (wJdx/x) with the combinations a and (Z 8 sin w t+U sin (w 1f+\//+7r) with the combinations 6 and 0.

Considering the extreme smallness which 15 the term S always has in practice with respect to the term U, the amplitude of the resulting oscillation R- has very closely the value CTI with the combinations a and d U+S cos [(m w )t+l,b+7r] with the combinations 6 and a and the current detected due to the second system of modulation has the value Ks cos wz-wazw with the combinations a and d COS [(w "10 If'lz/ll'w] with the combinations 7) and 0. The coefficient K depends on the detecting power of the tube, which power itself is a function of the degree of action of the heterodyne, hence of the electrostatic coupling C due to condenser 11, 13 or 11, 12.

As a definitive result it may be seen that:

The combinations (1 and d furnish a second current modulated in phase with the first. Hence, there exists amplification of the reception.

The combinations and c furnish two modulated currents in opposition, with the close approximations made in the calculation. Experience shows that these approximations correspond well to the actuality for the reason that when adjusting the electrostatic coupling (that is the coeificient called K in the calculation), the two modulations will destroy each other and the signal disappears on one of the two beats or surges.

Two thereof are favorable, the processes of frequency change coming to reinforce each other, while two are unfavorable. For instance, if it is desired to tune the heterodyne to a wave-length below the signal (w w the two processes reinforce each other by bringing the plate 11 closer to the plate 13.

Hence, reception or signal strength is increased, while the reception is practically suppresed by the coupling 11-12. The opposite condition holds true for w w Fig. 2 shows a similar circuit scheme comprising the use of a self-regenerative twogrid tube. The plate 13 may then be associated either directly with the end of the local generator or else with the plate 8, these two points being practically at the same high frequency potential.

It is to be understood, of course, that other schemes than those hereinbefore cited by way of example could be conceived without departing from the spirit of the invention.

l/Vhat I claim is:

1. The method of receiving electric signals comprising impressing the received signal on one of the grids of a vacuum tube, impressing locally generated oscillations upon another grid of the same vacuum tube, impressing the locally generated oscillations upon the first grid at the same time that the received signal is impressed thereon, and collecting the combined signal and local oscillations in the output circuit of the tube.

2. The method of receiving electric signals comprising heterodyning the received signals with local oscillations and at the same time modulating the received signals by the heterodyning oscillations.

3. A circuit arrangement comprising a resonator for receiving incoming signals, a tube comprising two grids, a device for generating local oscillations, means for impressing the local oscillations upon one of the grids, means for impressing the received signals on the same grid, and means for impressing the local oscillations of the said generating device upon the second grid so that the received signals are heterodyned and modulated at the same time.

4. A circuit arrangement comprising means for receiving incoming signals, a vacuum tube having at least two grids, means for generating local oscillations, the received signals being impressed upon one of the grids and the local oscillations being impressed upon the other grid and upon the plate, a condenser comprising one rotor and two independent stators, the rotor of the condenser being connected to the same grid which receives the incoming signals, the stators being respectively connected to the other grid and the plate, and means to collect the combined oscillations in the anode circuit of the tube.

5. The method of receiving electric signals which consists in impressing received signals upon the control electrode of a space discharge device, generating local oscillations, impressing the generated oscillations upon an independent control electrode of said discharge device and simultaneously impressing the generated oscillations upon the first control electrode with the impression of the received signals thereon.

HENRI JEAN JOSEPH MARIE de REGNAULD de BELLESCIZE. 

